'\" te
.\" Copyright (c) 2006, Sun Microsystems, Inc., All Rights Reserved
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.TH KSTAT_CREATE 9F "Sep 7, 2015"
.SH NAME
kstat_create \- create and initialize a new kstat
.SH SYNOPSIS
.nf
#include <sys/types.h>
#include <sys/kstat.h>



\fBkstat_t *\fR\fBkstat_create\fR(\fBconst char *\fR\fIks_module\fR, \fBint\fR \fIks_instance\fR,
     \fBconst char *\fR\fIks_name\fR, \fBconst char *\fR\fIks_class\fR, \fBuchar_t\fR \fIks_type\fR,
     \fBulong_t\fR \fIks_ndata\fR, \fBuchar_t\fR \fIks_flag\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI)
.SH PARAMETERS
.ne 2
.na
\fB\fIks_module\fR\fR
.ad
.RS 15n
The name of the provider's module (such as "\fBsd\fR", "\fBesp\fR", ...). The
"\fBcore\fR" kernel uses the name "unix".
.RE

.sp
.ne 2
.na
\fB\fIks_instance\fR\fR
.ad
.RS 15n
The provider's instance number, as from \fBddi_get_instance\fR(9F). Modules
which do not have a meaningful instance number should use \fB0\fR.
.RE

.sp
.ne 2
.na
\fB\fIks_name\fR\fR
.ad
.RS 15n
A pointer to a string that uniquely identifies this structure. Only
\fBKSTAT_STRLEN \(mi 1\fR characters are significant.
.RE

.sp
.ne 2
.na
\fB\fIks_class\fR\fR
.ad
.RS 15n
The general class that this kstat belongs to. The following classes are
currently in use: \fBdisk\fR, \fBtape\fR, \fBnet\fR, \fBcontroller\fR,
\fBvm\fR, \fBkvm\fR, \fBhat\fR, \fBstreams\fR, \fBkstat\fR, and \fBmisc\fR.
.RE

.sp
.ne 2
.na
\fB\fIks_type\fR\fR
.ad
.RS 15n
The type of \fBkstat\fR to allocate. Valid types are:
.sp
.ne 2
.na
\fB\fBKSTAT_TYPE_RAW\fR\fR
.ad
.RS 20n
Raw data; allows more than one data record per \fBkstat\fR.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_TYPE_NAMED\fR\fR
.ad
.RS 20n
Name=value pairs; allows more than one data record per \fBkstat\fR.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_TYPE_INTR\fR\fR
.ad
.RS 20n
Interrupt; only one data record per \fBkstat\fR.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_TYPE_IO\fR\fR
.ad
.RS 20n
\fBI/O\fR; only one data record per \fBkstat\fR.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_TYPE_TIMER\fR\fR
.ad
.RS 20n
Event timer statistics; allows more than one data record per \fBkstat\fR.
.RE

.RE

.sp
.ne 2
.na
\fB\fIks_ndata\fR\fR
.ad
.RS 15n
The number of type-specific data records to allocate.
.RE

.sp
.ne 2
.na
\fB\fIks_flag\fR\fR
.ad
.RS 15n
A bit-field of various flags for this \fBkstat\fR. \fIks_flag\fR is some
combination of:
.sp
.ne 2
.na
\fB\fBKSTAT_FLAG_VIRTUAL\fR\fR
.ad
.RS 25n
Tells \fBkstat_create()\fR not to allocate memory for the \fBkstat\fR data
section; instead, the driver will set the \fBks_data\fR field to point to the
data it wishes to export. This provides a convenient way to export existing
data structures.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_FLAG_WRITABLE\fR\fR
.ad
.RS 25n
Makes the \fBkstat\fR data section writable by root.
.RE

.sp
.ne 2
.na
\fB\fBKSTAT_FLAG_PERSISTENT\fR\fR
.ad
.RS 25n
Indicates that this \fBkstat\fR is to be persistent over time. For persistent
\fBkstat\fRs, \fBkstat_delete\fR(9F) simply marks the \fBkstat\fR as dormant; a
subsequent \fBkstat_create()\fR reactivates the kstat. This feature is provided
so that statistics are not lost across driver close/open (such as raw disk
\fBI/O\fR on a disk with no mounted partitions.) Note: Persistent \fBkstat\fRs
cannot be virtual, since \fBks_data\fR points to garbage as soon as the driver
goes away.
.RE

.RE

.SH DESCRIPTION
\fBkstat_create()\fR is used in conjunction with \fBkstat_install\fR(9F) to
allocate and initialize a \fBkstat\fR(9S) structure. The method is generally as
follows:
.sp
.LP
\fBkstat_create()\fR allocates and performs necessary system initialization of
a \fBkstat\fR(9S) structure. \fBkstat_create()\fR allocates memory for the
entire \fBkstat\fR (header plus data), initializes all header fields,
initializes the data section to all zeroes, assigns a unique kstat \fBID\fR
(\fBKID\fR), and puts the kstat onto the system's \fBkstat\fR chain. The
returned kstat is marked invalid because the provider (caller) has not yet had
a chance to initialize the data section.
.sp
.LP
After a successful call to \fBkstat_create()\fR the driver must perform any
necessary initialization of the data section (such as setting the name fields
in a \fBkstat\fR of type \fBKSTAT_TYPE_NAMED\fR). Virtual \fBkstat\fRs must
have the \fBks_data\fR field set at this time. The provider may also set the
\fBks_update\fR, \fBks_private\fR, and \fBks_lock\fR fields if necessary.
.sp
.LP
Once the \fBkstat\fR is completely initialized, \fBkstat_install\fR(9F) is used
to make the \fBkstat\fR accessible to the outside world.
.SH RETURN VALUES
If successful, \fBkstat_create()\fR returns a pointer to the allocated
\fBkstat\fR. \fINULL\fR is returned upon failure.
.SH CONTEXT
\fBkstat_create()\fR can be called from user or kernel context.
.SH EXAMPLES
\fBExample 1 \fRAllocating and Initializing a \fBkstat\fR Structure
.sp
.in +2
.nf
pkstat_t   *ksp;
   ksp = kstat_create(module, instance, name, class, type, ndata, flags);
   if (ksp) {
      /* ... provider initialization, if necessary */
      kstat_install(ksp);
   }
.fi
.in -2

.SH SEE ALSO
.BR kstat (3KSTAT),
.BR ddi_get_instance (9F),
.BR kstat_delete (9F),
.BR kstat_install (9F),
.BR kstat_named_init (9F),
.BR kstat (9S),
.BR kstat_named (9S)
.sp
.LP
\fIWriting Device Drivers\fR
